Several embodiments are known in the state of the art applied to detect defects which may appear in yarn bobbins.
We can mention thus patents JP-A-62-62938 and U.S. Pat. No. 5,138,151, which disclose methods to detect by means of image forming sensors of line by line reading, installed close to light sources in a station intercalated in a transfer line of the bobbins toward a storage or service area, which is embodied in a wrapping housing which delimitates an enclosure having access doors, which is crossed by the conveying line, providing means to rotate the bobbin to a given position, within said enclosure and when the doors have been closed to darken the inspection area.
This background has the drawback that as the inspection enclosure is intercalated in the conveying line itself, the inspection operation obliges to completely stop said conveying line during a very long time, because the closure of access doors and the accurate arrangement of means to rotate a support on which the bobbin is arranged have to be provided which means the system is slow, which makes that in addition to localize a possible defect two or three shootings of the image sensor are necessary, its use additionally meaning limitations as for the bobbin color and/or material, which makes difficult the general use of the method which is useful mainly for direct reflection bobbins. In addition, as this type of sensors only reads one line, the field embraced is very limited and shootings have to be done at very close points to achieve effective results. On the other hand, this system, as the bobbin rotation means interferes with the conveying line itself, has the likelihood to lead to error in the bobbin positioning which will produce reading inaccurateness of eventual defects to be assessed. Said technical issue does not allow either to arrange several in line inspection stations because for a correct operation it will be demanded that the inspection time has same length, which is not fit for the specific nature of each inspection cycle.
Patents JP-A-07-134105 and U.S. Pat. No. 5,359,408 disclose devices to inspect spinning bobbins with inspection stations also intercalated in the conveying line, but comprising matrix camera like means to form images, the second of said backgrounds disclosing arrangements applied to detect different possible defects by using several types of light sources such as ultraviolet rays, fluorescent or others.
However, said backgrounds do not contemplate the possibility to fully scan all bobbin surfaces, carrying out an inspection of multiple and different defects which may appear in spinning bobbins, in some cases checked twice or more times and by means of one or more inspection stations mounted on one or more quality control machines associated to a factory-fresh bobbins conveying line, with the peculiarity that it is adaptable to several sizes of bobbins and regardless said bobbins color and characteristics of the material.
The installation which is disclosed is applied to implement a bobbins inspecting method and system disclosed in the international application PCT/ES 97/00070 of same applicant where a series of relative arrangements of image forming sensors and light sources are proposed in order to obtain an effect of field deepness so that they allow to accurately focus eventual defects, at each sector scanned, which significantly facilitates their identification.